Forestry continues to be a vital part of many economies worldwide. As populations expand and the public continues to move into remote areas of country with dense vegetation, such as forest and woodlands, new and better ways of clearing vegetation and providing building materials for new dwellings are needed.
Implements for mechanized clearing and grooming of such vegetation have been developed over recent years, specifically designed for the harvest of forest lands.
These purpose built machines are very specialized in their specific purpose, not easily adapted to other uses. They are also expensive.
Some lower cost alternatives involve retrofitting vehicles such as excavators or backhoes with a swing frame and a boom apparatus have been used as an alternative to the purpose built. To retrofit an existing structure, one may start with a common chassis from a small bulldozer or excavator, which provides the locomotive means. This chassis is usually denoted as the car body or car chassis of the machine. A slew bearing, which provides a surface for pivotal rotation, is mounted on the chassis. Also typically integrated just above the slew bearing is the swing frame. The boom mechanism is typically attached to the swing frame in a way to azimuthally rotate to facilitate the raising and lowering of the boom, similar to a turret. This boom mechanism is typically outfitted with an implement for clearing or processing brush and trees. The skirt frame, which provides support for the cab housing, extends orthogonally from the swing frame and is typically cantilevered from the slew bearing. The combination of the skirt frame, the swing frame, and the slew bearing are often referred to as the main frame.
Also attached to the main frame above the skirt frame is a typically where the cab, or cabin, for the operator can be found. This cab region also typically provides attachments for electrical and other necessary components for operating the forest harvesting machine. It is this region that needs to be protected for the safety of the operator and where the roll over protection structures (ROPS) are found.
Because of the design structure requiring the skirt frame to be cantilevered from the slew bearing, such structures adapted from excavator car chassis and the like, are not capable of withstanding the intense loads and energy absorption needs commonly found in forestry applications, in particular with relationship to the main frame loads and roll over situations where the roll over is directed to the cab side, bringing the weight of the mainframe and boom structures to bear on the cab. In particular, it has been found that skirt frame designs of the prior art, for retrofitable off-road and forestry vehicles, are not sufficient to withstand ROPS loads without buckling in these situations.
When machines of the prior art have been subjected to these loads or need to absorb energy such as that created by falling trees, rollovers and the like, the region between the skirt frame and cab may likely buckle. Another possibility is that the cab structure itself will compress under the loads and stresses. When this happens the result may be operator death, or injury. In lesser cases; safety risks, equipment downtime issues, and expensive equipment repairs are seen.
U.S. Pat. No. 3,732,941 issued to Davis et al 15 May 1973 discloses a tractor body with a roll-over-protection structure and braces for providing a unitary structure which are welded to and integrated with the manufacture of the cab. While this does point to the felt need for such protection, the disclosed features are adapted to a tractor, and are not adequate to the added weight and structural requirements of a swing frame or boom structure. In addition, it is directed to the roll-over cage and is welded as part of the structure and does not have the retrofit ability and universality of the present invention to mount onto existing frames.
U.S. Pat. No. 3,866,942 issued to Dobeus et al 18 Feb., 1975 discloses a rollover protection apparatus which has legs that are secured to brackets on top of the operator's platform including connection points. The main point behind this disclosure is the addition of bushings to absorb the energy of a roll-over and direct it to the recoverable bending of the cage. While the approach may work for the conditions encountered by the inventor, it is believed that the disclosed structure is not only insufficient for the conditions of the present invention, but the addition of bushings as connection features, under the weight of the main frame, will be structurally incapable.
There are many manufactures of forestry excavator equipment, including John Deere, Hitachi, IMC and others. All of these manufactures have similar boom cab to swing frame assemblies, but prior art in the area of structures adapted from excavator car chassis have not provided a sufficiently safe ROPS structure.
Other solutions do not reinforce a main frame-to-cab interface sufficiently to absorb the loads and energies required without extensive damage to the structure.
This results in buckled swing frames which are expensive to repair.
It also results in unsafe conditions for the cab operator, should the cab buckle.
It also results in significant downtime to repair damaged frames.
Other approaches to the problem and capable of withstanding such loads are not retrofitable and require cutting, welding and/or other modification to the main frame and/or cab in order to be fitted.
Once modifications are made, and it is desired to return the equipment to its original condition, further cutting, welding and/or other modifications are often required.
It is therefore an object of the invention to provide a structure to reinforce the frame between the cab riser and the swing frame to improve load bearing capability.
It is another object of the invention that this structure provides improved rollover energy absorption capability by substantially transferring excessive energy of impact or load from the cab to the main frame.
It is another object of the invention to provide a safer work environment for the Operator by providing a buckle resistant cab and frame.
It is another objective of the invention to reinforce the cab and frame, which lessens downtime for repairs.
It is another object of the invention to allow the retrofit of a standard backhoe or excavation frame into forest harvesting machines, which can withstand. ROPS loads.
It is another object of the invention to reinforce the frame, which lessens downtime for repairs
It is another object in the invention to allow the retrofit of standard backhoe or excavation frames into forest harvesting machines without the need for substantial modification cutting or welding.
It is another object of the invention to allow the restoring of the standard backhoe or excavation frames from forest harvesting machines without the need for substantial modification, cutting or welding.
It is another object of the invention to provide a rollover protection structure which is located primarily under the operator.
It is another object of the invention to provide a rollover protection structure which is demountably attached.